My body clock is ticking

Question: I'm 36 and not in a relationship, however, I do want to have children. I don't really want to go to a sperm bank or go out and have a one night stand just to conceive but I'm worried that if I wait until I've found the 'right partner' it'll be too late. When should I start to panic about fertility?

Answer: Both men and women are usually said to reach their fertile peak at 24. There is a gradual slide for the next six years or so which accelerates during the 30s. However, there may be a fertility surge in the late 30s, sometimes resulting in the arrival of twins, because of the fertilisation of two eggs. By your late thirties, there's also more chance of you suffering one of the conditions that can lead to conception difficulties such as ovarian cysts, fibroid tumours in the uterus and endometriosis. Other than this there's no reason why you shouldn't be able to conceive in your late 30s and early 40s although it might take longer.

However, the older you are, the more risks there are in becoming pregnant. These include:

Down's syndrome: At the age of 29, you have a one in 1,000 chance of giving birth to a Down's syndrome baby. This rises to one in 380 at the age of 35, and one in 110 aged 40.

Hypertension: Also referred to as pre-eclampsia or toxaemia, high blood pressure is aggravated by pregnancy. A condition known as pregnancy-induced hypertension is more common in pregnancies when the mother is over 35.

Placenta praevia: The position of the placenta depends on where the embryo chooses to implant - usually towards the top of the back wall of the uterus. In this condition, however, the embryo has implanted in the lower part, so the placenta forms near the cervix, sometimes blocking it. Older women are slightly more susceptible.

Miscarriage: The miscarriage rate for women over 35 is about three times that of younger women. This is possibly because older women are at increased risk of carrying an abnormal foetus and this is nature's way of preventing the birth of severely handicapped infants.

Perinatal death: Although still very rare, older mothers are twice as likely to die during labour or in the first month after birth.

Many women do meet their life-partners in their late thirties or even early forties and go on to have healthy families, and choosing to become a single mother is not something anyone should take on lightly. However, it's worth considering all the factors above before deciding when to have children.